1. Field of the Invention
The present invention relates to atomic force microscopes, and more particularly, to a probe needle of a probe microscope, as well as the probe microscope that utilizes the probe needle.
2. Discussion of the Related Art
The probe needle arrangement of an atomic force microscope, such as a probe microscope, is constructed from a cantilever and a probe needle part which extends from the tip end of the cantilever in a direction substantially perpendicular to the direction of length of the cantilever. An atomic force microscope detects changes in the flexing (bending amount) of the cantilever caused by an interaction force between the probe needle part and a sample surface to be detected. Changes in the flexing of the cantilever are generally detected by an optical lever method. In the optical lever method, a light beam is projected onto the cantilever surface, and the flexing of the cantilever is detected by detecting changes in the direction of reflection. The surface shape of the sample can thus be detected with a high resolution by detecting changes in the flexing of the cantilever in this manner.
In industrial fields in which probe microscopes are widely used, and especially in the semiconductor field, there is an increasing need for the control of trenches and detecting of the surface shape of these trenches formed in samples. The objects of control in such cases are the shapes of the side surfaces of the trenches and the shape of the bottoms of the trenches. Such trenches have a narrow width and a high aspect ratio.
Accordingly, a boot type probe needle in which the tip end is flared has been proposed (An example is disclosed in, Yves Martin and H. Kumar Wickramasinghe, Appl. Phys. Lett. 64 (19), May 9, 1994, pp. 2498-2500, "Method for imaging sidewalls by atomic force microscopy"). In this device, the boot type probe needle is caused to undergo minute vibrations in the longitudinal and lateral directions, and the forces acting on the probe needle from the respective directions are measured. Feedback quantities corresponding to the forces acting on the probe respectively. In this way, samples having steep surface profiles are traced by the probe needle. However, in the case of a probe needle part which has edges pointing in the lateral directions, as in the boot type short needle, it is difficult to reduce the diameter of the tip end. As a result, it is difficult to insert the probe needle into the sample's trenches. Furthermore, since the probe needle part is caused to perform a reciprocating motion in the lateral direction perpendicular to the direction of length of the probe needle part in order to detect the force, there is a limit to the width of the trenches that can be measured.